For all those who can't access the student software for whatever reason: The source code.
If there is an other way to open documents you could do a memory dump and search for lua code. I've used that to recover unsaved code from the student software after it had crashed. You can even access protected code that way. But it could also work with other software that can open nspire documents.
edit: I've just tested that method with nspire_emu and ndless_installer.tns and it worked. So you can retrieve the source files from scripts even when you don't have the student software. Just do the memory dump and search for some lua pattern. There is some other stuff, probably from the OS, but the lua source code of the current document can also be found.